Index: uspace/lib/libc/Makefile.toolchain
===================================================================
--- uspace/lib/libc/Makefile.toolchain	(revision 99272a380ff885480a8f252b2e013a3ef7216b14)
+++ uspace/lib/libc/Makefile.toolchain	(revision f8ef6608009092d820081ab0f9bd7c8da8205b96)
@@ -30,5 +30,5 @@
 	-fexec-charset=UTF-8 -fwide-exec-charset=UTF-32 -finput-charset=UTF-8 \
 	-fno-builtin -Wall -Wextra -Wno-unused-parameter -Wmissing-prototypes \
-	-nostdlib -nostdinc -pipe -g
+	-Werror-implicit-function-declaration -nostdlib -nostdinc -pipe -g
 LFLAGS = -M -N $(SOFTINT_PREFIX)/libsoftint.a
 AFLAGS =
Index: uspace/lib/libc/generic/mem.c
===================================================================
--- uspace/lib/libc/generic/mem.c	(revision 99272a380ff885480a8f252b2e013a3ef7216b14)
+++ uspace/lib/libc/generic/mem.c	(revision f8ef6608009092d820081ab0f9bd7c8da8205b96)
@@ -96,5 +96,5 @@
 static void *unaligned_memcpy(void *dst, const void *src, size_t n)
 {
-	unsigned int i, j;
+	size_t i, j;
 	struct along *adst = dst;
 	const struct along *asrc = src;